Last time we counted there were more than 10 Scrum teams working on the product at the same time. Some difficulty is added by the fact that some of these teams do not deliver one product but multiple ones that are living at different levels of the stack. So we started sorting how we scale the scrum mode that works quite okay in the teams to the organization.
I had a certified PO course by Boris Gloger (I wouldn't necessary recommend though). However towards the end, he had some quite good ideas and comments about the whole enterprise scaling of scrum teams. I will list them as a reference.
- Domain Experts. Domain experts are a horizontal institution meeting once every week to discuss strategic issues of their expertise. I.E. architecture experts would discuss coding style guides and system architecture.
- Aligned sprints with aligned planning. He suggested having all sprints aligned to start and end at the same day. Before the sprint planning of teams, the product owners would gather to do a sprint planning for the larger organization, etc.
- Weekly schedule. He sketched a weekly schedule that would repeat during sprint times. Hence, all teams would have their sprint planning at the same time, would align their sprint reviews to be at the same time etc.
- Scrum of POs. The Scrum of Product Owners is much like a regular scrum. They have a scrum board where they track progress of all teams (moving user stories from left to right). This way you can see the overall organization progress at a glance.
We will try to implement these points ASAP.